Information Storage and Survival of Biological Systems at Temperatures Near Absolute Zero †

There have been numerous reports over the past fifty years of survival of organisms at very low temperatures. Many of these results have been summarized by Luyet and Gehenio.2 Among the metazoa, survival at low temperatures has been reported for nematodes, rotifers, tardigrades and artemia eggs.' Two general results seem to emerge from these cryobiology experiments: (1) If a living system can survive the damage caused by ice crystal formation and rapid dehydration on freezing and thawing, then it can survive arbitrarily low temperatures. (2) Those organisms which will survive dessication can be taken to arbitrarily low temperatures in the dessicated state. The survival of organisms after exposure to temperatures near absolute zero has special physical significance, for at these temperatures the only feature of the organism that persists is its structure. While each atom retains its position, its momentum goes to zero (disregarding zero point vibrational energy). Warming the system is a random process, so that the momentum distribution after exposure to temperatures near absolute zero is independent of the momentum distribution before freezing within the constraints imposed by the covalent bonding in the system. Consequently, if an organism survives this process, all of the information required for a viable system capable of responding in the appropriate biological way must be stored in its structure. To specify such an organism one would have to specify only a structure, and indeed to synthesize an organism one would need to synthesize the appropriate structure and would not be required to impose any energy or momentum distribution. In terms of statistical mechanics, specifying that a system is alive is a matter of specifying that it is in the appropriate subvolume of coordinate space. Because of the fundamental theoretical importance of survival near absolute zero, a series of experiments were designed to repeat with pre-